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 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
 #ifndef _BTRFS_CTREE_H_
 #define _BTRFS_CTREE_H_
 
 #include <linux/btrfs.h>
 #include <linux/types.h>
 #ifdef __KERNEL__
 #include <linux/stddef.h>
 #else
 #include <stddef.h>
 #endif
 
 /*
  * This header contains the structure definitions and constants used
  * by file system objects that can be retrieved using
  * the BTRFS_IOC_SEARCH_TREE ioctl.  That means basically anything that
  * is needed to describe a leaf node's key or item contents.
  */
 
 /* holds pointers to all of the tree roots */
 #define BTRFS_ROOT_TREE_OBJECTID 1ULL
 
 /* stores information about which extents are in use, and reference counts */
 #define BTRFS_EXTENT_TREE_OBJECTID 2ULL
 
 /*
  * chunk tree stores translations from logical -> physical block numbering
  * the super block points to the chunk tree
  */
 #define BTRFS_CHUNK_TREE_OBJECTID 3ULL
 
 /*
  * stores information about which areas of a given device are in use.
  * one per device.  The tree of tree roots points to the device tree
  */
 #define BTRFS_DEV_TREE_OBJECTID 4ULL
 
 /* one per subvolume, storing files and directories */
 #define BTRFS_FS_TREE_OBJECTID 5ULL
 
 /* directory objectid inside the root tree */
 #define BTRFS_ROOT_TREE_DIR_OBJECTID 6ULL
 
 /* holds checksums of all the data extents */
 #define BTRFS_CSUM_TREE_OBJECTID 7ULL
 
 /* holds quota configuration and tracking */
 #define BTRFS_QUOTA_TREE_OBJECTID 8ULL
 
 /* for storing items that use the BTRFS_UUID_KEY* types */
 #define BTRFS_UUID_TREE_OBJECTID 9ULL
 
 /* tracks free space in block groups. */
 #define BTRFS_FREE_SPACE_TREE_OBJECTID 10ULL
 
 /* Holds the block group items for extent tree v2. */
 #define BTRFS_BLOCK_GROUP_TREE_OBJECTID 11ULL
 
 /* device stats in the device tree */
 #define BTRFS_DEV_STATS_OBJECTID 0ULL
 
 /* for storing balance parameters in the root tree */
 #define BTRFS_BALANCE_OBJECTID -4ULL
 
 /* orphan objectid for tracking unlinked/truncated files */
 #define BTRFS_ORPHAN_OBJECTID -5ULL
 
 /* does write ahead logging to speed up fsyncs */
 #define BTRFS_TREE_LOG_OBJECTID -6ULL
 #define BTRFS_TREE_LOG_FIXUP_OBJECTID -7ULL
 
 /* for space balancing */
 #define BTRFS_TREE_RELOC_OBJECTID -8ULL
 #define BTRFS_DATA_RELOC_TREE_OBJECTID -9ULL
 
 /*
  * extent checksums all have this objectid
  * this allows them to share the logging tree
  * for fsyncs
  */
 #define BTRFS_EXTENT_CSUM_OBJECTID -10ULL
 
 /* For storing free space cache */
 #define BTRFS_FREE_SPACE_OBJECTID -11ULL
 
 /*
  * The inode number assigned to the special inode for storing
  * free ino cache
  */
 #define BTRFS_FREE_INO_OBJECTID -12ULL
 
 /* dummy objectid represents multiple objectids */
 #define BTRFS_MULTIPLE_OBJECTIDS -255ULL
 
 /*
  * All files have objectids in this range.
  */
 #define BTRFS_FIRST_FREE_OBJECTID 256ULL
 #define BTRFS_LAST_FREE_OBJECTID -256ULL
 #define BTRFS_FIRST_CHUNK_TREE_OBJECTID 256ULL
 
 
 /*
  * the device items go into the chunk tree.  The key is in the form
  * [ 1 BTRFS_DEV_ITEM_KEY device_id ]
  */
 #define BTRFS_DEV_ITEMS_OBJECTID 1ULL
 
 #define BTRFS_BTREE_INODE_OBJECTID 1
 
 #define BTRFS_EMPTY_SUBVOL_DIR_OBJECTID 2
 
 #define BTRFS_DEV_REPLACE_DEVID 0ULL
 
 /*
  * inode items have the data typically returned from stat and store other
  * info about object characteristics.  There is one for every file and dir in
  * the FS
  */
 #define BTRFS_INODE_ITEM_KEY        1
 #define BTRFS_INODE_REF_KEY     12
 #define BTRFS_INODE_EXTREF_KEY      13
 #define BTRFS_XATTR_ITEM_KEY        24
 
 /*
  * fs verity items are stored under two different key types on disk.
  * The descriptor items:
  * [ inode objectid, BTRFS_VERITY_DESC_ITEM_KEY, offset ]
  *
  * At offset 0, we store a btrfs_verity_descriptor_item which tracks the size
  * of the descriptor item and some extra data for encryption.
  * Starting at offset 1, these hold the generic fs verity descriptor.  The
  * latter are opaque to btrfs, we just read and write them as a blob for the
  * higher level verity code.  The most common descriptor size is 256 bytes.
  *
  * The merkle tree items:
  * [ inode objectid, BTRFS_VERITY_MERKLE_ITEM_KEY, offset ]
  *
  * These also start at offset 0, and correspond to the merkle tree bytes.  When
  * fsverity asks for page 0 of the merkle tree, we pull up one page starting at
  * offset 0 for this key type.  These are also opaque to btrfs, we're blindly
  * storing whatever fsverity sends down.
  */
 #define BTRFS_VERITY_DESC_ITEM_KEY  36
 #define BTRFS_VERITY_MERKLE_ITEM_KEY    37
 
 #define BTRFS_ORPHAN_ITEM_KEY       48
 /* reserve 2-15 close to the inode for later flexibility */
 
 /*
  * dir items are the name -> inode pointers in a directory.  There is one
  * for every name in a directory.  BTRFS_DIR_LOG_ITEM_KEY is no longer used
  * but it's still defined here for documentation purposes and to help avoid
  * having its numerical value reused in the future.
  */
 #define BTRFS_DIR_LOG_ITEM_KEY  60
 #define BTRFS_DIR_LOG_INDEX_KEY 72
 #define BTRFS_DIR_ITEM_KEY  84
 #define BTRFS_DIR_INDEX_KEY 96
 /*
  * extent data is for file data
  */
 #define BTRFS_EXTENT_DATA_KEY   108
 
 /*
  * extent csums are stored in a separate tree and hold csums for
  * an entire extent on disk.
  */
 #define BTRFS_EXTENT_CSUM_KEY   128
 
 /*
  * root items point to tree roots.  They are typically in the root
  * tree used by the super block to find all the other trees
  */
 #define BTRFS_ROOT_ITEM_KEY 132
 
 /*
  * root backrefs tie subvols and snapshots to the directory entries that
  * reference them
  */
 #define BTRFS_ROOT_BACKREF_KEY  144
 
 /*
  * root refs make a fast index for listing all of the snapshots and
  * subvolumes referenced by a given root.  They point directly to the
  * directory item in the root that references the subvol
  */
 #define BTRFS_ROOT_REF_KEY  156
 
 /*
  * extent items are in the extent map tree.  These record which blocks
  * are used, and how many references there are to each block
  */
 #define BTRFS_EXTENT_ITEM_KEY   168
 
 /*
  * The same as the BTRFS_EXTENT_ITEM_KEY, except it's metadata we already know
  * the length, so we save the level in key->offset instead of the length.
  */
 #define BTRFS_METADATA_ITEM_KEY 169
 
 #define BTRFS_TREE_BLOCK_REF_KEY    176
 
 #define BTRFS_EXTENT_DATA_REF_KEY   178
 
 #define BTRFS_EXTENT_REF_V0_KEY     180
 
 #define BTRFS_SHARED_BLOCK_REF_KEY  182
 
 #define BTRFS_SHARED_DATA_REF_KEY   184
 
 /*
  * block groups give us hints into the extent allocation trees.  Which
  * blocks are free etc etc
  */
 #define BTRFS_BLOCK_GROUP_ITEM_KEY 192
 
 /*
  * Every block group is represented in the free space tree by a free space info
  * item, which stores some accounting information. It is keyed on
  * (block_group_start, FREE_SPACE_INFO, block_group_length).
  */
 #define BTRFS_FREE_SPACE_INFO_KEY 198
 
 /*
  * A free space extent tracks an extent of space that is free in a block group.
  * It is keyed on (start, FREE_SPACE_EXTENT, length).
  */
 #define BTRFS_FREE_SPACE_EXTENT_KEY 199
 
 /*
  * When a block group becomes very fragmented, we convert it to use bitmaps
  * instead of extents. A free space bitmap is keyed on
  * (start, FREE_SPACE_BITMAP, length); the corresponding item is a bitmap with
  * (length / sectorsize) bits.
  */
 #define BTRFS_FREE_SPACE_BITMAP_KEY 200
 
 #define BTRFS_DEV_EXTENT_KEY    204
 #define BTRFS_DEV_ITEM_KEY  216
 #define BTRFS_CHUNK_ITEM_KEY    228
 
 /*
  * Records the overall state of the qgroups.
  * There's only one instance of this key present,
  * (0, BTRFS_QGROUP_STATUS_KEY, 0)
  */
 #define BTRFS_QGROUP_STATUS_KEY         240
 /*
  * Records the currently used space of the qgroup.
  * One key per qgroup, (0, BTRFS_QGROUP_INFO_KEY, qgroupid).
  */
 #define BTRFS_QGROUP_INFO_KEY           242
 /*
  * Contains the user configured limits for the qgroup.
  * One key per qgroup, (0, BTRFS_QGROUP_LIMIT_KEY, qgroupid).
  */
 #define BTRFS_QGROUP_LIMIT_KEY          244
 /*
  * Records the child-parent relationship of qgroups. For
  * each relation, 2 keys are present:
  * (childid, BTRFS_QGROUP_RELATION_KEY, parentid)
  * (parentid, BTRFS_QGROUP_RELATION_KEY, childid)
  */
 #define BTRFS_QGROUP_RELATION_KEY       246
 
 /*
  * Obsolete name, see BTRFS_TEMPORARY_ITEM_KEY.
  */
 #define BTRFS_BALANCE_ITEM_KEY  248
 
 /*
  * The key type for tree items that are stored persistently, but do not need to
  * exist for extended period of time. The items can exist in any tree.
  *
  * [subtype, BTRFS_TEMPORARY_ITEM_KEY, data]
  *
  * Existing items:
  *
  * - balance status item
  *   (BTRFS_BALANCE_OBJECTID, BTRFS_TEMPORARY_ITEM_KEY, 0)
  */
 #define BTRFS_TEMPORARY_ITEM_KEY    248
 
 /*
  * Obsolete name, see BTRFS_PERSISTENT_ITEM_KEY
  */
 #define BTRFS_DEV_STATS_KEY     249
 
 /*
  * The key type for tree items that are stored persistently and usually exist
  * for a long period, eg. filesystem lifetime. The item kinds can be status
  * information, stats or preference values. The item can exist in any tree.
  *
  * [subtype, BTRFS_PERSISTENT_ITEM_KEY, data]
  *
  * Existing items:
  *
  * - device statistics, store IO stats in the device tree, one key for all
  *   stats
  *   (BTRFS_DEV_STATS_OBJECTID, BTRFS_DEV_STATS_KEY, 0)
  */
 #define BTRFS_PERSISTENT_ITEM_KEY   249
 
 /*
  * Persistently stores the device replace state in the device tree.
  * The key is built like this: (0, BTRFS_DEV_REPLACE_KEY, 0).
  */
 #define BTRFS_DEV_REPLACE_KEY   250
 
 /*
  * Stores items that allow to quickly map UUIDs to something else.
  * These items are part of the filesystem UUID tree.
  * The key is built like this:
  * (UUID_upper_64_bits, BTRFS_UUID_KEY*, UUID_lower_64_bits).
  */
 #if BTRFS_UUID_SIZE != 16
 #error "UUID items require BTRFS_UUID_SIZE == 16!"
 #endif
 #define BTRFS_UUID_KEY_SUBVOL   251 /* for UUIDs assigned to subvols */
 #define BTRFS_UUID_KEY_RECEIVED_SUBVOL  252 /* for UUIDs assigned to
                          * received subvols */
 
 /*
  * string items are for debugging.  They just store a short string of
  * data in the FS
  */
 #define BTRFS_STRING_ITEM_KEY   253
 
 /* Maximum metadata block size (nodesize) */
 #define BTRFS_MAX_METADATA_BLOCKSIZE            65536
 
 /* 32 bytes in various csum fields */
 #define BTRFS_CSUM_SIZE 32
 
 /* csum types */
 enum btrfs_csum_type {
     BTRFS_CSUM_TYPE_CRC32   = 0,
     BTRFS_CSUM_TYPE_XXHASH  = 1,
     BTRFS_CSUM_TYPE_SHA256  = 2,
     BTRFS_CSUM_TYPE_BLAKE2  = 3,
 };
 
 /*
  * flags definitions for directory entry item type
  *
  * Used by:
  * struct btrfs_dir_item.type
  *
  * Values 0..7 must match common file type values in fs_types.h.
  */
 #define BTRFS_FT_UNKNOWN    0
 #define BTRFS_FT_REG_FILE   1
 #define BTRFS_FT_DIR        2
 #define BTRFS_FT_CHRDEV     3
 #define BTRFS_FT_BLKDEV     4
 #define BTRFS_FT_FIFO       5
 #define BTRFS_FT_SOCK       6
 #define BTRFS_FT_SYMLINK    7
 #define BTRFS_FT_XATTR      8
 #define BTRFS_FT_MAX        9
 
 /*
  * The key defines the order in the tree, and so it also defines (optimal)
  * block layout.
  *
  * objectid corresponds to the inode number.
  *
  * type tells us things about the object, and is a kind of stream selector.
  * so for a given inode, keys with type of 1 might refer to the inode data,
  * type of 2 may point to file data in the btree and type == 3 may point to
  * extents.
  *
  * offset is the starting byte offset for this key in the stream.
  *
  * btrfs_disk_key is in disk byte order.  struct btrfs_key is always
  * in cpu native order.  Otherwise they are identical and their sizes
  * should be the same (ie both packed)
  */
 struct btrfs_disk_key {
     __le64 objectid;
     __u8 type;
     __le64 offset;
 } __attribute__ ((__packed__));
 
 struct btrfs_key {
     __u64 objectid;
     __u8 type;
     __u64 offset;
 } __attribute__ ((__packed__));
 
 struct btrfs_dev_item {
     /* the internal btrfs device id */
     __le64 devid;
 
     /* size of the device */
     __le64 total_bytes;
 
     /* bytes used */
     __le64 bytes_used;
 
     /* optimal io alignment for this device */
     __le32 io_align;
 
     /* optimal io width for this device */
     __le32 io_width;
 
     /* minimal io size for this device */
     __le32 sector_size;
 
     /* type and info about this device */
     __le64 type;
 
     /* expected generation for this device */
     __le64 generation;
 
     /*
      * starting byte of this partition on the device,
      * to allow for stripe alignment in the future
      */
     __le64 start_offset;
 
     /* grouping information for allocation decisions */
     __le32 dev_group;
 
     /* seek speed 0-100 where 100 is fastest */
     __u8 seek_speed;
 
     /* bandwidth 0-100 where 100 is fastest */
     __u8 bandwidth;
 
     /* btrfs generated uuid for this device */
     __u8 uuid[BTRFS_UUID_SIZE];
 
     /* uuid of FS who owns this device */
     __u8 fsid[BTRFS_UUID_SIZE];
 } __attribute__ ((__packed__));
 
 struct btrfs_stripe {
     __le64 devid;
     __le64 offset;
     __u8 dev_uuid[BTRFS_UUID_SIZE];
 } __attribute__ ((__packed__));
 
 struct btrfs_chunk {
     /* size of this chunk in bytes */
     __le64 length;
 
     /* objectid of the root referencing this chunk */
     __le64 owner;
 
     __le64 stripe_len;
     __le64 type;
 
     /* optimal io alignment for this chunk */
     __le32 io_align;
 
     /* optimal io width for this chunk */
     __le32 io_width;
 
     /* minimal io size for this chunk */
     __le32 sector_size;
 
     /* 2^16 stripes is quite a lot, a second limit is the size of a single
      * item in the btree
      */
     __le16 num_stripes;
 
     /* sub stripes only matter for raid10 */
     __le16 sub_stripes;
     struct btrfs_stripe stripe;
     /* additional stripes go here */
 } __attribute__ ((__packed__));
 
 #define BTRFS_FREE_SPACE_EXTENT 1
 #define BTRFS_FREE_SPACE_BITMAP 2
 
 struct btrfs_free_space_entry {
     __le64 offset;
     __le64 bytes;
     __u8 type;
 } __attribute__ ((__packed__));
 
 struct btrfs_free_space_header {
     struct btrfs_disk_key location;
     __le64 generation;
     __le64 num_entries;
     __le64 num_bitmaps;
 } __attribute__ ((__packed__));
 
 #define BTRFS_HEADER_FLAG_WRITTEN   (1ULL << 0)
 #define BTRFS_HEADER_FLAG_RELOC     (1ULL << 1)
 
 /* Super block flags */
 /* Errors detected */
 #define BTRFS_SUPER_FLAG_ERROR      (1ULL << 2)
 
 #define BTRFS_SUPER_FLAG_SEEDING    (1ULL << 32)
 #define BTRFS_SUPER_FLAG_METADUMP   (1ULL << 33)
 #define BTRFS_SUPER_FLAG_METADUMP_V2    (1ULL << 34)
 #define BTRFS_SUPER_FLAG_CHANGING_FSID  (1ULL << 35)
 #define BTRFS_SUPER_FLAG_CHANGING_FSID_V2 (1ULL << 36)
 
 
 /*
  * items in the extent btree are used to record the objectid of the
  * owner of the block and the number of references
  */
 
 struct btrfs_extent_item {
     __le64 refs;
     __le64 generation;
     __le64 flags;
 } __attribute__ ((__packed__));
 
 struct btrfs_extent_item_v0 {
     __le32 refs;
 } __attribute__ ((__packed__));
 
 
 #define BTRFS_EXTENT_FLAG_DATA      (1ULL << 0)
 #define BTRFS_EXTENT_FLAG_TREE_BLOCK    (1ULL << 1)
 
 /* following flags only apply to tree blocks */
 
 /* use full backrefs for extent pointers in the block */
 #define BTRFS_BLOCK_FLAG_FULL_BACKREF   (1ULL << 8)
 
 /*
  * this flag is only used internally by scrub and may be changed at any time
  * it is only declared here to avoid collisions
  */
 #define BTRFS_EXTENT_FLAG_SUPER     (1ULL << 48)
 
 struct btrfs_tree_block_info {
     struct btrfs_disk_key key;
     __u8 level;
 } __attribute__ ((__packed__));
 
 struct btrfs_extent_data_ref {
     __le64 root;
     __le64 objectid;
     __le64 offset;
     __le32 count;
 } __attribute__ ((__packed__));
 
 struct btrfs_shared_data_ref {
     __le32 count;
 } __attribute__ ((__packed__));
 
 struct btrfs_extent_inline_ref {
     __u8 type;
     __le64 offset;
 } __attribute__ ((__packed__));
 
 /* dev extents record free space on individual devices.  The owner
  * field points back to the chunk allocation mapping tree that allocated
  * the extent.  The chunk tree uuid field is a way to double check the owner
  */
 struct btrfs_dev_extent {
     __le64 chunk_tree;
     __le64 chunk_objectid;
     __le64 chunk_offset;
     __le64 length;
     __u8 chunk_tree_uuid[BTRFS_UUID_SIZE];
 } __attribute__ ((__packed__));
 
 struct btrfs_inode_ref {
     __le64 index;
     __le16 name_len;
     /* name goes here */
 } __attribute__ ((__packed__));
 
 struct btrfs_inode_extref {
     __le64 parent_objectid;
     __le64 index;
     __le16 name_len;
     __u8   name[];
     /* name goes here */
 } __attribute__ ((__packed__));
 
 struct btrfs_timespec {
     __le64 sec;
     __le32 nsec;
 } __attribute__ ((__packed__));
 
 struct btrfs_inode_item {
     /* nfs style generation number */
     __le64 generation;
     /* transid that last touched this inode */
     __le64 transid;
     __le64 size;
     __le64 nbytes;
     __le64 block_group;
     __le32 nlink;
     __le32 uid;
     __le32 gid;
     __le32 mode;
     __le64 rdev;
     __le64 flags;
 
     /* modification sequence number for NFS */
     __le64 sequence;
 
     /*
      * a little future expansion, for more than this we can
      * just grow the inode item and version it
      */
     __le64 reserved[4];
     struct btrfs_timespec atime;
     struct btrfs_timespec ctime;
     struct btrfs_timespec mtime;
     struct btrfs_timespec otime;
 } __attribute__ ((__packed__));
 
 struct btrfs_dir_log_item {
     __le64 end;
 } __attribute__ ((__packed__));
 
 struct btrfs_dir_item {
     struct btrfs_disk_key location;
     __le64 transid;
     __le16 data_len;
     __le16 name_len;
     __u8 type;
 } __attribute__ ((__packed__));
 
 #define BTRFS_ROOT_SUBVOL_RDONLY    (1ULL << 0)
 
 /*
  * Internal in-memory flag that a subvolume has been marked for deletion but
  * still visible as a directory
  */
 #define BTRFS_ROOT_SUBVOL_DEAD      (1ULL << 48)
 
 struct btrfs_root_item {
     struct btrfs_inode_item inode;
     __le64 generation;
     __le64 root_dirid;
     __le64 bytenr;
     __le64 byte_limit;
     __le64 bytes_used;
     __le64 last_snapshot;
     __le64 flags;
     __le32 refs;
     struct btrfs_disk_key drop_progress;
     __u8 drop_level;
     __u8 level;
 
     /*
      * The following fields appear after subvol_uuids+subvol_times
      * were introduced.
      */
 
     /*
      * This generation number is used to test if the new fields are valid
      * and up to date while reading the root item. Every time the root item
      * is written out, the "generation" field is copied into this field. If
      * anyone ever mounted the fs with an older kernel, we will have
      * mismatching generation values here and thus must invalidate the
      * new fields. See btrfs_update_root and btrfs_find_last_root for
      * details.
      * the offset of generation_v2 is also used as the start for the memset
      * when invalidating the fields.
      */
     __le64 generation_v2;
     __u8 uuid[BTRFS_UUID_SIZE];
     __u8 parent_uuid[BTRFS_UUID_SIZE];
     __u8 received_uuid[BTRFS_UUID_SIZE];
     __le64 ctransid; /* updated when an inode changes */
     __le64 otransid; /* trans when created */
     __le64 stransid; /* trans when sent. non-zero for received subvol */
     __le64 rtransid; /* trans when received. non-zero for received subvol */
     struct btrfs_timespec ctime;
     struct btrfs_timespec otime;
     struct btrfs_timespec stime;
     struct btrfs_timespec rtime;
     __le64 reserved[8]; /* for future */
 } __attribute__ ((__packed__));
 
 /*
  * Btrfs root item used to be smaller than current size.  The old format ends
  * at where member generation_v2 is.
  */
 static inline __u32 btrfs_legacy_root_item_size(void)
 {
     return offsetof(struct btrfs_root_item, generation_v2);
 }
 
 /*
  * this is used for both forward and backward root refs
  */
 struct btrfs_root_ref {
     __le64 dirid;
     __le64 sequence;
     __le16 name_len;
 } __attribute__ ((__packed__));
 
 struct btrfs_disk_balance_args {
     /*
      * profiles to operate on, single is denoted by
      * BTRFS_AVAIL_ALLOC_BIT_SINGLE
      */
     __le64 profiles;
 
     /*
      * usage filter
      * BTRFS_BALANCE_ARGS_USAGE with a single value means '0..N'
      * BTRFS_BALANCE_ARGS_USAGE_RANGE - range syntax, min..max
      */
     union {
         __le64 usage;
         struct {
             __le32 usage_min;
             __le32 usage_max;
         };
     };
 
     /* devid filter */
     __le64 devid;
 
     /* devid subset filter [pstart..pend) */
     __le64 pstart;
     __le64 pend;
 
     /* btrfs virtual address space subset filter [vstart..vend) */
     __le64 vstart;
     __le64 vend;
 
     /*
      * profile to convert to, single is denoted by
      * BTRFS_AVAIL_ALLOC_BIT_SINGLE
      */
     __le64 target;
 
     /* BTRFS_BALANCE_ARGS_* */
     __le64 flags;
 
     /*
      * BTRFS_BALANCE_ARGS_LIMIT with value 'limit'
      * BTRFS_BALANCE_ARGS_LIMIT_RANGE - the extend version can use minimum
      * and maximum
      */
     union {
         __le64 limit;
         struct {
             __le32 limit_min;
             __le32 limit_max;
         };
     };
 
     /*
      * Process chunks that cross stripes_min..stripes_max devices,
      * BTRFS_BALANCE_ARGS_STRIPES_RANGE
      */
     __le32 stripes_min;
     __le32 stripes_max;
 
     __le64 unused[6];
 } __attribute__ ((__packed__));
 
 /*
  * store balance parameters to disk so that balance can be properly
  * resumed after crash or unmount
  */
 struct btrfs_balance_item {
     /* BTRFS_BALANCE_* */
     __le64 flags;
 
     struct btrfs_disk_balance_args data;
     struct btrfs_disk_balance_args meta;
     struct btrfs_disk_balance_args sys;
 
     __le64 unused[4];
 } __attribute__ ((__packed__));
 
 enum {
     BTRFS_FILE_EXTENT_INLINE   = 0,
     BTRFS_FILE_EXTENT_REG      = 1,
     BTRFS_FILE_EXTENT_PREALLOC = 2,
     BTRFS_NR_FILE_EXTENT_TYPES = 3,
 };
 
 struct btrfs_file_extent_item {
     /*
      * transaction id that created this extent
      */
     __le64 generation;
     /*
      * max number of bytes to hold this extent in ram
      * when we split a compressed extent we can't know how big
      * each of the resulting pieces will be.  So, this is
      * an upper limit on the size of the extent in ram instead of
      * an exact limit.
      */
     __le64 ram_bytes;
 
     /*
      * 32 bits for the various ways we might encode the data,
      * including compression and encryption.  If any of these
      * are set to something a given disk format doesn't understand
      * it is treated like an incompat flag for reading and writing,
      * but not for stat.
      */
     __u8 compression;
     __u8 encryption;
     __le16 other_encoding; /* spare for later use */
 
     /* are we inline data or a real extent? */
     __u8 type;
 
     /*
      * disk space consumed by the extent, checksum blocks are included
      * in these numbers
      *
      * At this offset in the structure, the inline extent data start.
      */
     __le64 disk_bytenr;
     __le64 disk_num_bytes;
     /*
      * the logical offset in file blocks (no csums)
      * this extent record is for.  This allows a file extent to point
      * into the middle of an existing extent on disk, sharing it
      * between two snapshots (useful if some bytes in the middle of the
      * extent have changed
      */
     __le64 offset;
     /*
      * the logical number of file blocks (no csums included).  This
      * always reflects the size uncompressed and without encoding.
      */
     __le64 num_bytes;
 
 } __attribute__ ((__packed__));
 
 struct btrfs_csum_item {
     __u8 csum;
 } __attribute__ ((__packed__));
 
 struct btrfs_dev_stats_item {
     /*
      * grow this item struct at the end for future enhancements and keep
      * the existing values unchanged
      */
     __le64 values[BTRFS_DEV_STAT_VALUES_MAX];
 } __attribute__ ((__packed__));
 
 #define BTRFS_DEV_REPLACE_ITEM_CONT_READING_FROM_SRCDEV_MODE_ALWAYS 0
 #define BTRFS_DEV_REPLACE_ITEM_CONT_READING_FROM_SRCDEV_MODE_AVOID  1
 
 struct btrfs_dev_replace_item {
     /*
      * grow this item struct at the end for future enhancements and keep
      * the existing values unchanged
      */
     __le64 src_devid;
     __le64 cursor_left;
     __le64 cursor_right;
     __le64 cont_reading_from_srcdev_mode;
 
     __le64 replace_state;
     __le64 time_started;
     __le64 time_stopped;
     __le64 num_write_errors;
     __le64 num_uncorrectable_read_errors;
 } __attribute__ ((__packed__));
 
 /* different types of block groups (and chunks) */
 #define BTRFS_BLOCK_GROUP_DATA      (1ULL << 0)
 #define BTRFS_BLOCK_GROUP_SYSTEM    (1ULL << 1)
 #define BTRFS_BLOCK_GROUP_METADATA  (1ULL << 2)
 #define BTRFS_BLOCK_GROUP_RAID0     (1ULL << 3)
 #define BTRFS_BLOCK_GROUP_RAID1     (1ULL << 4)
 #define BTRFS_BLOCK_GROUP_DUP       (1ULL << 5)
 #define BTRFS_BLOCK_GROUP_RAID10    (1ULL << 6)
 #define BTRFS_BLOCK_GROUP_RAID5         (1ULL << 7)
 #define BTRFS_BLOCK_GROUP_RAID6         (1ULL << 8)
 #define BTRFS_BLOCK_GROUP_RAID1C3       (1ULL << 9)
 #define BTRFS_BLOCK_GROUP_RAID1C4       (1ULL << 10)
 #define BTRFS_BLOCK_GROUP_RESERVED  (BTRFS_AVAIL_ALLOC_BIT_SINGLE | \
                      BTRFS_SPACE_INFO_GLOBAL_RSV)
 
 #define BTRFS_BLOCK_GROUP_TYPE_MASK (BTRFS_BLOCK_GROUP_DATA |    \
                      BTRFS_BLOCK_GROUP_SYSTEM |  \
                      BTRFS_BLOCK_GROUP_METADATA)
 
 #define BTRFS_BLOCK_GROUP_PROFILE_MASK  (BTRFS_BLOCK_GROUP_RAID0 |   \
                      BTRFS_BLOCK_GROUP_RAID1 |   \
                      BTRFS_BLOCK_GROUP_RAID1C3 | \
                      BTRFS_BLOCK_GROUP_RAID1C4 | \
                      BTRFS_BLOCK_GROUP_RAID5 |   \
                      BTRFS_BLOCK_GROUP_RAID6 |   \
                      BTRFS_BLOCK_GROUP_DUP |     \
                      BTRFS_BLOCK_GROUP_RAID10)
 #define BTRFS_BLOCK_GROUP_RAID56_MASK   (BTRFS_BLOCK_GROUP_RAID5 |   \
                      BTRFS_BLOCK_GROUP_RAID6)
 
 #define BTRFS_BLOCK_GROUP_RAID1_MASK    (BTRFS_BLOCK_GROUP_RAID1 |   \
                      BTRFS_BLOCK_GROUP_RAID1C3 | \
                      BTRFS_BLOCK_GROUP_RAID1C4)
 
 /*
  * We need a bit for restriper to be able to tell when chunks of type
  * SINGLE are available.  This "extended" profile format is used in
  * fs_info->avail_*_alloc_bits (in-memory) and balance item fields
  * (on-disk).  The corresponding on-disk bit in chunk.type is reserved
  * to avoid remappings between two formats in future.
  */
 #define BTRFS_AVAIL_ALLOC_BIT_SINGLE    (1ULL << 48)
 
 /*
  * A fake block group type that is used to communicate global block reserve
  * size to userspace via the SPACE_INFO ioctl.
  */
 #define BTRFS_SPACE_INFO_GLOBAL_RSV (1ULL << 49)
 
 #define BTRFS_EXTENDED_PROFILE_MASK (BTRFS_BLOCK_GROUP_PROFILE_MASK | \
                      BTRFS_AVAIL_ALLOC_BIT_SINGLE)
 
 static inline __u64 chunk_to_extended(__u64 flags)
 {
     if ((flags & BTRFS_BLOCK_GROUP_PROFILE_MASK) == 0)
         flags |= BTRFS_AVAIL_ALLOC_BIT_SINGLE;
 
     return flags;
 }
 static inline __u64 extended_to_chunk(__u64 flags)
 {
     return flags & ~BTRFS_AVAIL_ALLOC_BIT_SINGLE;
 }
 
 struct btrfs_block_group_item {
     __le64 used;
     __le64 chunk_objectid;
     __le64 flags;
 } __attribute__ ((__packed__));
 
 struct btrfs_free_space_info {
     __le32 extent_count;
     __le32 flags;
 } __attribute__ ((__packed__));
 
 #define BTRFS_FREE_SPACE_USING_BITMAPS (1ULL << 0)
 
 #define BTRFS_QGROUP_LEVEL_SHIFT        48
 static inline __u16 btrfs_qgroup_level(__u64 qgroupid)
 {
     return (__u16)(qgroupid >> BTRFS_QGROUP_LEVEL_SHIFT);
 }
 
 /*
  * is subvolume quota turned on?
  */
 #define BTRFS_QGROUP_STATUS_FLAG_ON     (1ULL << 0)
 /*
  * RESCAN is set during the initialization phase
  */
 #define BTRFS_QGROUP_STATUS_FLAG_RESCAN     (1ULL << 1)
 /*
  * Some qgroup entries are known to be out of date,
  * either because the configuration has changed in a way that
  * makes a rescan necessary, or because the fs has been mounted
  * with a non-qgroup-aware version.
  * Turning qouta off and on again makes it inconsistent, too.
  */
 #define BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT   (1ULL << 2)
 
 #define BTRFS_QGROUP_STATUS_VERSION        1
 
 struct btrfs_qgroup_status_item {
     __le64 version;
     /*
      * the generation is updated during every commit. As older
      * versions of btrfs are not aware of qgroups, it will be
      * possible to detect inconsistencies by checking the
      * generation on mount time
      */
     __le64 generation;
 
     /* flag definitions see above */
     __le64 flags;
 
     /*
      * only used during scanning to record the progress
      * of the scan. It contains a logical address
      */
     __le64 rescan;
 } __attribute__ ((__packed__));
 
 struct btrfs_qgroup_info_item {
     __le64 generation;
     __le64 rfer;
     __le64 rfer_cmpr;
     __le64 excl;
     __le64 excl_cmpr;
 } __attribute__ ((__packed__));
 
 struct btrfs_qgroup_limit_item {
     /*
      * only updated when any of the other values change
      */
     __le64 flags;
     __le64 max_rfer;
     __le64 max_excl;
     __le64 rsv_rfer;
     __le64 rsv_excl;
 } __attribute__ ((__packed__));
 
 struct btrfs_verity_descriptor_item {
     /* Size of the verity descriptor in bytes */
     __le64 size;
     /*
      * When we implement support for fscrypt, we will need to encrypt the
      * Merkle tree for encrypted verity files. These 128 bits are for the
      * eventual storage of an fscrypt initialization vector.
      */
     __le64 reserved[2];
     __u8 encryption;
 } __attribute__ ((__packed__));
 
 #endif /* _BTRFS_CTREE_H_ */

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